Commit 55cc3768 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

libbpf: Add link-based API for tcx 



Implement tcx BPF link support for libbpf.

The bpf_program__attach_fd() API has been refactored slightly in order to pass
bpf_link_create_opts pointer as input.

A new bpf_program__attach_tcx() has been added on top of this which allows for
passing all relevant data via extensible struct bpf_tcx_opts.

The program sections tcx/ingress and tcx/egress correspond to the hook locations
for tc ingress and egress, respectively.

For concrete usage examples, see the extensive selftests that have been
developed as part of this series.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230719140858.13224-5-daniel@iogearbox.net


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent fe20ce3a

tools/lib/bpf/bpf.c

+18 −2
Original line number Diff line number Diff line
@@ -719,9 +719,9 @@ int bpf_link_create(int prog_fd, int target_fd, 
		    const struct bpf_link_create_opts *opts)

{

	const size_t attr_sz = offsetofend(union bpf_attr, link_create);

	__u32 target_btf_id, iter_info_len;

	__u32 target_btf_id, iter_info_len, relative_id;

	int fd, err, relative_fd;

	union bpf_attr attr;

	int fd, err;



	if (!OPTS_VALID(opts, bpf_link_create_opts))

		return libbpf_err(-EINVAL);
@@ -783,6 +783,22 @@ int bpf_link_create(int prog_fd, int target_fd, 
		if (!OPTS_ZEROED(opts, netfilter))

			return libbpf_err(-EINVAL);

		break;

	case BPF_TCX_INGRESS:

	case BPF_TCX_EGRESS:

		relative_fd = OPTS_GET(opts, tcx.relative_fd, 0);

		relative_id = OPTS_GET(opts, tcx.relative_id, 0);

		if (relative_fd && relative_id)

			return libbpf_err(-EINVAL);

		if (relative_id) {

			attr.link_create.tcx.relative_id = relative_id;

			attr.link_create.flags |= BPF_F_ID;

		} else {

			attr.link_create.tcx.relative_fd = relative_fd;

		}

		attr.link_create.tcx.expected_revision = OPTS_GET(opts, tcx.expected_revision, 0);

		if (!OPTS_ZEROED(opts, tcx))

			return libbpf_err(-EINVAL);

		break;

	default:

		if (!OPTS_ZEROED(opts, flags))

			return libbpf_err(-EINVAL);

tools/lib/bpf/bpf.h

+5 −0
Original line number Diff line number Diff line
@@ -401,6 +401,11 @@ struct bpf_link_create_opts { 
			__s32 priority;

			__u32 flags;

		} netfilter;

		struct {

			__u32 relative_fd;

			__u32 relative_id;

			__u64 expected_revision;

		} tcx;

	};

	size_t :0;

};

tools/lib/bpf/libbpf.c

+49 −9
Original line number Diff line number Diff line
@@ -134,6 +134,7 @@ static const char * const link_type_name[] = { 
	[BPF_LINK_TYPE_KPROBE_MULTI]		= "kprobe_multi",

	[BPF_LINK_TYPE_STRUCT_OPS]		= "struct_ops",

	[BPF_LINK_TYPE_NETFILTER]		= "netfilter",

	[BPF_LINK_TYPE_TCX]			= "tcx",

};



static const char * const map_type_name[] = {
@@ -11854,11 +11855,10 @@ static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_li 
}



static struct bpf_link *

bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id,

		       const char *target_name)

bpf_program_attach_fd(const struct bpf_program *prog,

		      int target_fd, const char *target_name,

		      const struct bpf_link_create_opts *opts)

{

	DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,

			    .target_btf_id = btf_id);

	enum bpf_attach_type attach_type;

	char errmsg[STRERR_BUFSIZE];

	struct bpf_link *link;
@@ -11876,7 +11876,7 @@ bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id 
	link->detach = &bpf_link__detach_fd;



	attach_type = bpf_program__expected_attach_type(prog);

	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);

	link_fd = bpf_link_create(prog_fd, target_fd, attach_type, opts);

	if (link_fd < 0) {

		link_fd = -errno;

		free(link);
@@ -11892,19 +11892,54 @@ bpf_program__attach_fd(const struct bpf_program *prog, int target_fd, int btf_id 
struct bpf_link *

bpf_program__attach_cgroup(const struct bpf_program *prog, int cgroup_fd)

{

	return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");

	return bpf_program_attach_fd(prog, cgroup_fd, "cgroup", NULL);

}



struct bpf_link *

bpf_program__attach_netns(const struct bpf_program *prog, int netns_fd)

{

	return bpf_program__attach_fd(prog, netns_fd, 0, "netns");

	return bpf_program_attach_fd(prog, netns_fd, "netns", NULL);

}



struct bpf_link *bpf_program__attach_xdp(const struct bpf_program *prog, int ifindex)

{

	/* target_fd/target_ifindex use the same field in LINK_CREATE */

	return bpf_program__attach_fd(prog, ifindex, 0, "xdp");

	return bpf_program_attach_fd(prog, ifindex, "xdp", NULL);

}



struct bpf_link *

bpf_program__attach_tcx(const struct bpf_program *prog, int ifindex,

			const struct bpf_tcx_opts *opts)

{

	LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);

	__u32 relative_id;

	int relative_fd;



	if (!OPTS_VALID(opts, bpf_tcx_opts))

		return libbpf_err_ptr(-EINVAL);



	relative_id = OPTS_GET(opts, relative_id, 0);

	relative_fd = OPTS_GET(opts, relative_fd, 0);



	/* validate we don't have unexpected combinations of non-zero fields */

	if (!ifindex) {

		pr_warn("prog '%s': target netdevice ifindex cannot be zero\n",

			prog->name);

		return libbpf_err_ptr(-EINVAL);

	}

	if (relative_fd && relative_id) {

		pr_warn("prog '%s': relative_fd and relative_id cannot be set at the same time\n",

			prog->name);

		return libbpf_err_ptr(-EINVAL);

	}



	link_create_opts.tcx.expected_revision = OPTS_GET(opts, expected_revision, 0);

	link_create_opts.tcx.relative_fd = relative_fd;

	link_create_opts.tcx.relative_id = relative_id;

	link_create_opts.flags = OPTS_GET(opts, flags, 0);



	/* target_fd/target_ifindex use the same field in LINK_CREATE */

	return bpf_program_attach_fd(prog, ifindex, "tcx", &link_create_opts);

}



struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog,
@@ -11926,11 +11961,16 @@ struct bpf_link *bpf_program__attach_freplace(const struct bpf_program *prog, 
	}



	if (target_fd) {

		LIBBPF_OPTS(bpf_link_create_opts, target_opts);



		btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);

		if (btf_id < 0)

			return libbpf_err_ptr(btf_id);



		return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");

		target_opts.target_btf_id = btf_id;



		return bpf_program_attach_fd(prog, target_fd, "freplace",

					     &target_opts);

	} else {

		/* no target, so use raw_tracepoint_open for compatibility

		 * with old kernels

tools/lib/bpf/libbpf.h

+15 −0
Original line number Diff line number Diff line
@@ -733,6 +733,21 @@ LIBBPF_API struct bpf_link * 
bpf_program__attach_netfilter(const struct bpf_program *prog,

			      const struct bpf_netfilter_opts *opts);



struct bpf_tcx_opts {

	/* size of this struct, for forward/backward compatibility */

	size_t sz;

	__u32 flags;

	__u32 relative_fd;

	__u32 relative_id;

	__u64 expected_revision;

	size_t :0;

};

#define bpf_tcx_opts__last_field expected_revision



LIBBPF_API struct bpf_link *

bpf_program__attach_tcx(const struct bpf_program *prog, int ifindex,

			const struct bpf_tcx_opts *opts);



struct bpf_map;



LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(const struct bpf_map *map);

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -397,4 +397,5 @@ LIBBPF_1.3.0 { 
		bpf_obj_pin_opts;

		bpf_prog_detach_opts;

		bpf_program__attach_netfilter;

		bpf_program__attach_tcx;

} LIBBPF_1.2.0;